Stress urinary incontinence refers to a disease of leaking urine without the urge to urinate in abdominal pressures (exercise, cough, sneezing, etc.) due to functional disorder of the urethral sphincter muscle having a function that tightens the urethra in order not to leak urine from the bladder. Stress urinary incontinence is a disease shown in both males and females, and causes in a female are mainly sphincter muscle functional disorders due to pregnancy and delivery, gynecological surgeries, and aging, and causes in a male are sphincter muscle disorders due to surgeries for prostate gland enlargement and prostate gland cancer. Physical therapy (pelvic floor muscle training) is usually carried out in an early stage of a treatment for stress urinary incontinence, but is invalid in a case of having a moderate or severer symptom. As a surgical treatment, the urethral sling surgery (that is a vaginal operation, in which an artificial tape is placed under the urethra to hold the urethra) is generally broadly performed for female stress urinary incontinence and favorable results have been attained, but the urethral sling surgery has a defect such that a foreign material is left inside the body and, for male stress urinary incontinence, there is no effective surgical treatment that can be domestically performed. For a minimally invasive surgical treatment, a treatment of injecting bovine collagen into the periurethral zone (an endoscope is transurethrally inserted and collagen is injected to the membranous urethra through an endoscope) is carried out in some cases, but a treatment continuing effect is not attained because of recurrence within 1 to 3 months due to being absorbed within several weeks after the injection, and also for stress urinary incontinence after a prostate gland operation, an effectiveness itself is not more than 20%, which is defective (Non-patent Document 1). What is more, since collagen is derived from a bovine tissue, there is a problem that a risk of development of transferable spongiform encephalopathy cannot be completely denied.
The disease has a very high prevalence rate and impairs quality of life, and there is no minimally invasive, highly effective therapeutic method, and therefore, there is an urgent need to develop a minimally invasive, highly effective therapeutic method. The urethral injection treatment using cultured autologous skeletal muscle-derived stem cells has been already clinically applied to a treatment for stress urinary incontinence abroad (Non-patent Document 2), but because of difficulty of securing cultured cells to be used in injection (culture method, environment) and safety problems, development of a new noninvasive surgical therapeutic method and clinical introduction have been demanded.
A stress urinary incontinence treatment using adipose tissue-derived mesenchymal stem cells (called Adipose-derived stem cells: ASC, Adipose-derived regeneration cells: ADRC, Adipose-derived mesenchymal stem cells: AT-MSC, AD-MSC, etc.) has not been performed in Japan and abroad. It was reported that ASC is injected into the periurethral zone of a rat to differentiate to a smooth muscle (Non-patent Document 3), but no functional data showing improvement of stress urinary incontinence has been shown. The research group of the present inventors reported in the patent applications mentioned above that cultured ASC is injected into the periurethral zone using a stress urinary incontinent rat model to thus obtain increase of a urethral internal pressure and improvement of urinary incontinence (Patent Document 1).